Kappstein E-Mobiltiy

B3 Motor

With the goal of developing an extremely lightweight and above all compact wheel hub motor, Kappstein is introducing the new B3 motor weighing just 2.5 kg and with the diameter of a geared hub, this powerful lightweight is designed as a direct drive, making it much quieter than standard geared motors and providing a very smooth riding performance.

As a special highlight and despite its compact size, the motor features an internal controller and torque sensor. It’s at its best when combined with Kappstein’s Doppio CX bottom-bracket drive system. This enables the construction of an extremely lightweight electric bike with two or more gears using very compact and intelligently designed components. It also sets new standards in e-mobility, especially in terms of performance and innovative content. The motor is suitable for both chain- and belt-driven bikes. It’s maintenance-free, permits 9-spline mounting for a cassette or sprocket, and excels with superior heat dissipation.


Type: direct drive (BLDC) motor
Nominal Power: 250W
Maximum Power: 400W
Voltage: 36V
Controller: internal
Torque Sensor: internal
Weight: 2.6kg
Diameter: 110mm
Torque: 25Nm
Performance: very smooth and silent
Axle: M10, Thru Axle
Other: no visible screws on casing

The B3 is the evolution of the KA Classic motor which in the early 2000s was one of the first BLDC motors in the European market. The majority of ebikes in the European market were equipped with this motor at the time which was distributed under the Toprun brand. Already then it was ahead of its time with an internal controller and torque sensor. 

The B3 is adapted for the OEM as a series engine and can not be retrofitted. The accommodation of the battery and optionally a display unit as well as the wiring is customized in cooperation with the customer for each model. You get an individual solution according to your wishes. We are open to any new project and see our strength above all in the the customer service and our flexibility.

For further questions please do not hesitate to contact us: info@kappstein.de